For large pneumatic actuators or drives with a pneumatic volume larger than or of at least approximately 2000 cm3, it is desirable from a process-engineering point of view to realize a quick operation of a control valve to be controlled by the actuator, which, in the area of process-engineering, is commonly realized by deploying one or several so called pneumatic boosters or amplifiers. For each of these additionally connected boosters, additional pneumatic valves, such as quick exhaust valves, have to be deployed, in order to satisfy the operational requirements of the respective processing plant. The pneumatic connection of the boosters to the position controller and to the pneumatic actuator is cumbersome even by itself. Additionally it is difficult to set the respective individual operating characteristics of the device in the light of the desired positioning control when employing further pneumatic components.
The volume booster can be attached between a pneumatic position controller and a pneumatic control actuator having a control armature, such as a control valve, of a processing plant, and serves for aerating and/or for de-aerating, which shall for example operate a control valve of the processing plant. A processing plant serves for processing a process-technical fluid, such as petrochemical fluids, foodstuff-fluids, such as brewery-juices, in large scale.
German Patent Application Publication DE 10 2009 015 999 A1 describes a piloted pressure proportional valve. Upon a corresponding control, a volume stream amplification function can be attributed to the valve. The valve can include an electrically operable aeration valve and an electrically operable de-aeration valve, both of which are connected to a piloting chamber of the proportional valve, the piloting chamber being subjected to pressurized air. The pressure proportional valve includes a blocking function for the pneumatic actuator, when a predetermined actual working pressure falls below a predetermined desired working pressure, by closing the aeration valve and opening the de-aeration valve. Through pneumatically connecting both valves, the necessity for tubing is increased. Should further additional pneumatic amplifiers, such as boosters, be utilized, in order to supply a further volume stream amplification function to the pressure proportional valve, further valves would have to be included, which would have to be adapted to the desired control behavior of the position controller and which would thus increase the necessity for tubing even further.
In case of the very large volume pneumatic actuator (or drive), for example having a displacement volume of above 2000 cm3, it is difficult to realize small pneumatic signal changes and large pneumatic signal changes, that is: to realize respective pressure changes, within the pneumatic working chamber of the pneumatic drive. For smaller positioning changes of the control valve to be controlled by the pneumatic control actuator, overshooting over the desired control position can occur due to friction forces and corresponding lengthy response time. In case of long control paths to be passed, this can lead to overshoot allowed by the large amounts of air present. In order to realize the correspondingly large amounts of air from a position controller into the pneumatic actuator, extra boosters can be deployed, which demand a cumbersome pneumatic connection. In case of a serial or parallel connection of multiple boosters, pneumatic signal deterioration has to be accepted, which requires complex and complicated adaptions of the control system due to different response characteristics and different dynamic behavior of the individual boosters.
The exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings.